The invention relates to a roll-forming or bending machine, by which an angled or rounded and simultaneously tapered hollow body or similar workpiece can be formed from a material blank, with the roll-forming or bending machine having at least one tapered cylinder and at least one counter element, between which the material blank can be pressed in a forming manner and of which at least the one or more counter elements have an elastic surface.
Exhaust pipes of modern motor vehicles frequently have an exhaust tailpiece, which is not just round or oval, but also expands increasingly conically. In other fields of technology, for example, in furniture construction, comparable hollow bodies are also needed, which have an angled, round, or conical shape and which simultaneously taper, wherein, here, an oval or tri-oval cross section should also be understood as a round or rounded cross section and, for example, a rectangular or polygonal cross section should also be understood as an angled cross section.
Such angled or round and simultaneously tapered workpieces can be produced only with considerable expense. Bending rolls are already known, which have a steel upper roll and a lower roll with an elastic surface made from polyurethane plastic, between which a sheet-metal blank can be made into a round and conical shape simultaneously, with the roll forming of the workpiece being regulated by the contact pressure force and the diameter of the upper roll on the lower roll. In order to equalize the different rotational speeds, which the conical upper roll has in the region of its different roll diameter, the lower roll can be divided into individual roll sections that can rotate independently from each other. Because the lower roll has a corresponding multiple-part and complicated construction and because the rolls of previously known bending machines must feature a correspondingly large roll minimum diameter, in these previously known devices only large workpieces could be produced.
For example, from DE 175 20 01, a roll-forming or bending machine is already known, which is constructed as a sheet-metal rolling machine and in which, a first roll with a solid sleeve, a second driving roll with elastic sleeve acting as a counter element, and their driving devices, as well as a tensioning device for moving the two rolls towards or away from each other, are arranged in a support frame. To be able to use both cylindrical and also conical rolls on the previously known sheet-metal rolling machine and in order to be able to form both cylindrical or rounded as well as tapered workpieces accordingly with the help of the previously known sheet-metal rolling machine, an elongated lever arm, which can pivot about a vertical axis and on which the second roll is held so that it can rotate and on which a force amplifier is built that moves the second roll into the pressure position and into the released position, is attached to the support frame, wherein control devices are provided for changing the pressure exerted by the force amplifier on the rolls. Also for this two-roll sheet-metal rolling machine, the rolls have a comparatively robust and bulky construction, so that only relatively large workpieces can be formed.